HR: 1340h
AN: A43C-1422    [Abstracts]
TI: Aerosol Light Absorption and Scattering in Mexico City: Comparison With Las Vegas, NV, and Los Angeles, CA.
AU: * Paredes-Miranda, G
EM: gparedes@physics.unr.edu
AF: Department of Physics, University of Nevada Reno, 1664 N. Virginia St., Reno, NV 89557- 0042, United States
AU: Arnott, W P
EM: patarnott@physics.unr.edu
AF: Department of Physics, University of Nevada Reno, 1664 N. Virginia St., Reno, NV 89557- 0042, United States
AU: Gaffney, J S
EM: jsgaffney@ualr.edu
AF: Department of Chemistry and Graduate Research Institute, University of Arkansas Chemistry 2801 South University Avenue SCLB RM 451, Little Rock, AR 72204, United States
AU: Marley, N A
EM: namarley@ualr.edu
AF: Department of Chemistry and Graduate Research Institute, University of Arkansas Chemistry 2801 South University Avenue SCLB RM 451, Little Rock, AR 72204, United States
AU: Campbell, D
EM: Dave.Campbell@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Fujita, E
EM: Erik.Fujita@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
AB: Aerosol light scattering and absorption measurements were deployed in and near Mexico City in March 2006 as part of the Megacity Impacts on Regional and Global Environments (MIRAGE). The primary site in Mexico City was an urban site at Instituto Mexicano del Petroleo (Mexican Oil Institute, denoted by IMP). Similar campaigns were held in Las Vegas, NV in January-February, 2003; and Los Angeles, CA at numerous sites during all seasons from 2003 through 2007. The IMP site gave in-situ characterization of the Mexico City plume under favorable wind conditions. The photoacoustic instrument (PAS) used at IMP operates at 532 nm, and conveniently allowed for characterization of gaseous absorption at this wavelength as well. Light scattering measurements are accomplished within the PAS by the reciprocal nephelometery method. In Mexico City the aerosol absorption coefficient typically varies between 20 and 180 Mm^-1 during the course of the day and significant diurnal variation of the aerosol single scattering albedo was observed probably as a consequence of secondary aerosol formation. We will present the diurnal variation of the scattering and absorption as well as the single scattering albedo and fraction of absorption due to gases at the IMP site and compare with Las Vegas diurnal variation. Mexico City ‘breaths' more during the course of the day than Las Vegas, Nevada in part because the latitude of Mexico City resulted in more direct solar radiation. Further insight on the meteorological connections and population dynamics will be discussed.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0360 Radiation: transmission and scattering
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting